Factory Smoke
![Smokestacks from an oil refinery in Commerce City, Colorado, are shown pumping black smoke into the atmosphere.](/sites/default/files/media/images/oil_refinery_commerce_city.jpg)
UCAR/Caryle Calvin
Factories like this oil refinery in Commerce City, Colorado, add air pollution to the atmosphere in the form of toxic metals, particulates, and many different gases. Some of those gases lead to the formation of ground-level ozone as well as contribute to climate warming due to the greenhouse effect.